It takes a scrappy little documentary like “12 O’Clock Boys” to make you realize how little of the American underclass gets seen by this country’s mass media, let alone presented with as few preconceptions as possible. Directed over three years by first-timer Lotfy Nathan, the movie’s a short, pungent, ambiguous portrait of the poorer sections of Baltimore and the primarily young men who get their kicks riding dirt bikes through the streets en masse, popping wheelies and dodging the police.

Because they’re young, black, male, and loud, the riders are regarded by local TV news anchors with barely disguised panic. Nathan just takes his camera into their homes and garages, painting them as neither saints nor sinners but people with few options and a need for short-term release. The riders — it’s not at all accurate to call them a gang — take videos of themselves and post them on YouTube, where they’re viewed by a global audience; it’s a genuine subculture with a handful of windows looking in.

Yes, it’s dangerous, and, yes, there’s an uneasy imbalance of power with the Baltimore police, who stay out of chases with the riders but still fence them in using spotter helicopters and prowl-cars. There are occasional fatalities, with the cops blaming reckless bikers and the bikers blaming overzealous cops. The footage only underscores a festering community anger.

As a depiction of extralegal activity, “12 O’Clock Boys” is eye-opening but sometimes needlessly ambiguous. The other half of Nathan’s movie is more problematic, focusing as it does on Pug, who’s 12 when the movie opens in 2010 and will do anything to join the 12 O’Clock Boys. As the movie unfolds over two years, he trades his kid-size ATV for a dirt bike — it’s unclear where it comes from — and his youth for an increasingly rebellious life on the streets.

His mother, Coco, despairs but doesn’t do much to stop him, and the final scenes of “12 O’Clock Boys,” in which Pug has grown into a swaggering teen braggart, risk losing our sympathy. But then comes a scene where another man takes Pug’s dirt bike for a spin and doesn’t come back, and you see in the kid’s eyes the loss of everything that matters to him. Just because you don’t want to look at it doesn’t mean it’s not there.

“Every city has a Pug, every ’hood has a Pug,” says one veteran of the Baltimore dirt-bike scene. “This is what the ghetto produces. Yeah, we gonna ride.”